Apparatus for decompressing multiple codes in a single clock cycle

Abstract

A decompressor for generally providing more than four bits of decompressed data. The decompressor of this invention is capable of decoding four non-long horizontal codes in parallel and selecting either the decompressed data of the first code if it generates four or more bits of decompressed data or selecting the decompressed data of the first code with a combination of the decompressed data of the following codes if the first code generates less than four bits of decompressed data. This decompressor decompresses the long horizontal codes (codes which generate more than four bits of data) separately.

We claim: 
     
       1. An apparatus for decompressing compressed image data comprising: a) means for receiving a series of a given number of at least three codes in one clock cycle and identifying them as long horizontal codes or non-long horizontal codes, the given number of at least three codes equaling a desired given minimum number of bits of decompressed data to be generated during the same one clock cycle;   b) parallel decoding means operatively connected to said receiving means;   c) long code decoding means operatively connected to said receiving means;   d) said receiving means including means for sending, during the same one clock cycle, the identified long horizontal codes to said long code decoding means and sending, during the same one clock cycle, the identified non-long horizontal codes in a non-long horizontal code series of one or more non-long horizontal codes to said parallel decoding means;   e) said parallel decoding means having a plurality of decoding means for decoding in parallel during the same one clock cycle each of the non-long horizontal codes received during such cycle by said decoding means;   f) one of said plurality of parallel decoding means having a decoder being so constructed and arranged to receive the first code of the non-long horizontal code series, the remaining of said plurality of parallel decoding means being so constructed and arranged to receive all of the remaining codes in the non-long horizontal code series;   g) said parallel decoding means, for each of the remaining non-long horizontal codes received thereby, decoding during the same one clock cycle its respective remaining code for all possible conditions of the number of bits that can be generated during the same one clock cycle by the non-long horizontal codes preceding each respective one of the remaining codes, the possible conditions being a minimum cumulative number of bits that can be generated by the non-long horizontal code series preceding such respective one of the remaining codes up to one bit less than the desired given minimum number of bits of decompressed data to be generated during the same one clock cycle;   h) said parallel decoding means for each of the remaining codes of the non-long horizontal code series comprising a designated number of decoders equaling the number of all possible conditions of the number of bits that can be generated by the non-long horizontal codes preceding each respective one of the remaining codes, and when the designated number of the decoders for receiving a particular code is more than one, each of said decoders of said designated number of decoders decodes in parallel during the same clock cycle its respective code for a different particular one of the possible conditions;   i) non-long horizontal code decompressed data selecting means operatively connected to said parallel decoding means for selecting during the same one clock cycle: i 1 . the decompressed data of the first code in the non-long horizontal code series if either the first code generates at least the desired given minimum number of bits of decompressed data or the first codes is the only code in the non-long horizontal code series,   i 2 . the decompressed data of the first code in the non-long horizontal code series and the decompressed data for the second code in the non-long horizontal code series, which corresponds to the possible decompressed data condition that matches the actual number of bits generated by the decompressed data of the first code, if the number of bits of decompressed data generated by the first code is less than the desired given minimum number of bits and either the first two codes generate a cumulative number of bits of decompressed data which is at least the desired given minimum number of bits or the second code is the last code in the non-long horizontal code series, and   i 3 . the decompressed data of the first two codes in the non-long horizontal code series and any one or more of the codes in the non-long horizontal code series following the first two codes in the same manner as the selection of the decompressed data of the first two codes in the non-long horizontal code series if the cumulative number of bits of decompressed data generated by the first two codes is less than the desired given minimum number of bits, determined by either the first two codes and the one or more codes generating a cumulative total of at least the desired given minimum number of bits and the cumulative number of bits of decompressed data generated by the codes in the non-long horizontal code series prior to the last code for which the decompressed data is selected is less than the desired given minimum number of bits or the last code selected is the last code in the non-long horizontal code series, and     j) long horizontal code decompressed data selecting means operatively connected to said long code decoding means for selecting the decompressed data of a long code sent to said long decoding means.   
     
     
       2. The apparatus for decompressing compressed image data in accordance with claim 1 wherein the given number of at least three codes is three codes and the given minimum number of bits is three. 
     
     
       3. The apparatus for decompressing compressed image data in accordance with claim 1 wherein the given number of at least three codes is four codes and the given minimum number of bits is four. 
     
     
       4. The apparatus for decompressing compressed image data in accordance with claim 1 wherein the given number of at least three codes is more than four codes and the given minimum number of bits is equal to the given number of codes. 
     
     
       5. The apparatus for decompressing compressed image data in accordance with claim 1 wherein said receiving means includes means: a) for sending within the same clock cycle received, only one identified long horizontal code to said long code decoding means if such identified long horizontal code is the first code of the series of identified codes; and   b) for sending within the same clock cycle received, a series of one or more consecutive identified non-long horizontal codes to said parallel decoding means if one of such identified non-long horizontal codes is the first code in the series of identified codes.   
     
     
       6. The apparatus for decompressing compressed image data in accordance with claim 5 wherein the given number of at least three codes is three codes and the given minimum number of bits is three. 
     
     
       7. The apparatus for decompressing compressed image data in accordance with claim 5 wherein the given number of at least three codes is four codes and the given minimum number of bits is four. 
     
     
       8. The apparatus for decompressing compressed image data in accordance with claim 5 wherein the given number of at least three codes is more than four codes and the given minimum number of bits is equal to the given number of codes. 
     
     
       9. The apparatus for decompressing compressed image data in accordance with claim 1 wherein: a) said receiving means includes means for sending, within the same clock cycle received, only one identified long horizontal code to said long code decoding means if such identified long horizontal code is the first code of the series of identified codes and said non-long horizontal code selecting means selects, within the same clock cycle, the decompressed data of the only one identified long horizontal code;   b) said receiving means further includes means for sending, within the same clock cycle received, a series of one or more consecutive identified non-long horizontal codes to said parallel decoding means if one of such identified non-long horizontal codes is the first code in the series of identified codes and said parallel decoding means, within the same clock cycle, generates decompressed data of all non-long horizontal codes in the non-long horizontal code series received thereby from said receiving means and said non-long horizontal code and said selecting means, within the same clock cycle, selects the appropriate decompressed data of the non-long horizontal codes; and   c) said receiving means including means for sending either one long horizontal code to said long code decoding means or a non-long horizontal code series of one or more non-long horizontal codes to said parallel decoding means during one clock cycle.   
     
     
       10. The apparatus for decompressing compressed image data in accordance with claim 9 wherein the given number of at least three codes is three codes and the given minimum number of bits is three. 
     
     
       11. The apparatus for decompressing compressed image data in accordance with claim 9 wherein the given number of at least three codes is four codes and the given minimum number of bits is four. 
     
     
       12. The apparatus for decompressing compressed image data in accordance with claim 9 wherein the given number of at least three codes is more than four codes and the given minimum number of bits is equal to the given number of codes.